Automatic low oil cutoff device for oil burner tanks



W. B. MAURO Dec. 10, 1968 AUTOMATIC LOW OIL'CUTOFF DEVICE FOR OIL BURNER TANKS 2 Sheets-Sheet 1 Filed July ll, 1966 mwmmlla.

mum/7% Maia/ 0 AWN N H w. B. MAURO 3,415,958

AUTOMATIC LOW OIL CUTOFF DEVICE FOR OIL BURNER TANKS Dec. 10, 1968 2 Sheets-Sheet 2 Filed July 11, 1966 Mil/t B. aura United States Patent 01 56cc 3,415,958 Patented Dec. 10, 1968 3,415,958 AUTOMATIC LOW OIL CUTOFF DEVICE FOR 01L BURNER TANKS William B. Mauro, 172 Lawrence Ave., Brooklyn, N.Y. 11230 Filed July 11, 1966, Ser. No. 564,414 1 Claim. (Cl. 20084) ABSTRACT OF THE DISCLOSURE A float-actuated electrical switch mechanism for use in an oil tank to operate at a predetermined level of oil'. Said switch mechanism utilizing a two part cylindrical body having an electrical contact and diaphragm assembly tightly sealed between the two seections. The assembly includes a support plate and a flexible diaphragm overlying one another and having wafer-thin contacts engaging each other. Means is provided for moving the diaphragm from the support plate when the oil reaches a predetermined level.

This invention relates generally to oil tanks and more particularly to new and useful improvements in automatic float-actuated electrical switch mechanism for controlling the operation of the oil burner.

Oil tanks are often placed underground so that the condition of the oil therein cannot be seen. Sludge accumulates on the bottom of the tank and spoils the quality of the oil and good practice requires that this sludge be removed.

It is, therefore, a principal object of the present invention to provide an automatic float actuated switch mechanism associated with an oil tank that positively stops the operation of the oil burner at a predetermined level of the oil in the tank so that the sludge or water is not drawn into the oil burner to clog oil lines, strainers or the nozzles thereof, or damage the burner.

It is another object of the invention to eliminate the need for service calls and particularly repeat calls and the undue expense in the operation of oil burners in the home.

Another object of the invention is to provide a floatactuated switch mechanism for an oil tank that is readily assembled and easily installed in the oil tank.

A further object of the invention is to provide such a float-actuated switch mechanism with means for shielding the oil in the tank from the electrical contacts thereof.

A further object of the invention is to provide an automatic float-switch mechanism that can be mounted in the tank so that any spill or overflow from the fill vent pipes cannot damage any parts of its controls.

A still further object of the invention is to provide a low level, low voltage, electrical float-actuated switch mechanism that is simple in construction and positive in use, automatic, eflicient and safe in operation, and can be operated from the low voltage on the relay side of the burner.

Broadly, the invention comprises a casing installed in an opening in the top of the oil tank. The casing houses stationary and movable electrical contacts in a sealed manner. A pipe depends into the tank from the casing and extending through the pipe is a ball chain having a washer assembly on its bottom end which extends outwardly of the pipe and is attached at its upper end to a diaphragm supporting one movable switch contact. A float is slidably mounted on the pipe and is adapted to engage the washer assembly on the wire when the oil reaches a predetermined level and pull the diaphragm downwardly breaking the circuit through the main switch which controls the oil burner.

For further comprehension of the invention and of the objects and advantages thereof, reference Will be had to the appended claim in which the various novel features of the invention are more particularly set forth.

In the accompanying drawings forming a material part of this disclosure:

FIGURE 1 is a pictorial view of an oil tank and oil burner installation, a float-actuated switch embodying the invention being shown applied to the oil tank and connected to the main switch controlling the oil burner.

FIG. 2 is a perspective view of the float-actuated switch of FIG. 1, parts being shown broken away.

FIG. 3 is a sectional view through the float-actuated switch showing the switch parts in closed position.

FIG. 4 is an enlarged diagrammatical view of the switch showing the switch parts in open position, parts being shown broken away, and

FIG. 5 is a spread perspective view of the switch parts shown in FIG. 4.

Referring now in detail to the drawings in FIG. 1, there is shown an oil tank 10 shown underground for supplying oil to an electric-operated oil burner 12 of a furnace 14. The tank has a fill pipe 16 at the top thereof which may as well serve as a vent, and an outlet 18 at its bottom thereof. A delivery pipe 20 connects the outlet 18 with the inlet of the burner 12, that sprays the oil into the furnace 14 through its gun barrel 22. A valve 24 controls the flow of oil to the burner 12. The oil burner is electrically-operated and is controlled from a main switch 26 in stalled on the furnace 14. The main switch is connected to an electric wall receptacle 27 by a cable 28 and plug 30 and is connected to the burner 12 by a cable 32 to control the operation of the same in response to a thermostat thereof or other means.

In accordance with the present invention, an automatic float-actuated switch device 34 is installed in the oil tank 10 for controlling the operation of the main switch 26 and the oil burner 12. The switch device 34 comprises a threaded bottom section 38 and atop hollow terminal box section 40 fastened to each other by screws 42 passing through holes in the bottom of box section 40 and through holes of parts to be aligned therewith in the manner to be described and threaded into holes 46 in the top of the bottom section 38.

The bottom section 38 has a round hollow shank with a threaded side wall 50 and a closed bottom wall 52, with a central internally screw threaded hole 56. A squareshaped flange 58 extends radially outwardly around and from the top of the side wall 50, the flange 58 having the holes 44 at its corners.

The top section 40 of the casing includes an inverted square-shaped shallow cover or lid 60 with depending side walls 62. The side Walls 62 are open at the rear side and have opposing hinge bosses 64 that are connected by hinge pins 66 to sides of bottom part 68 of terminal box section 40.

The internal switch parts include generally a squareshaped insulating plate body 70, a similarly square-shaped rubber-like cooperating body diaphragm 72 and a separating insulated gasket 74. Contact strips or bus bars 76 and 78 of wafer-thin metal are secured by adhesive to the top surface of the insulating plate 70 and respectively extend around the opposite side edges thereof. The strip 76 is secured by adhesive 76' to the under surface of the plate 70 therebelow to provide an upper contact. The opposite strip 78 is secured by adhesive 78' to the top surface of the diaphragm 72 and lies under the contact strip 76 for normal engagement therewith through gasket opening 74'. Thus the contact strips 76 and 78 have respectively spring clip terminals 80 and 82 for connection with low voltage wire extending from the main control switch 26 through cable 26.

The flexible diaphragm 72 is similar in width to plate 70 and with the spacing gasket 74 covers and seals the engagcable ends of the contact strips 74 and 76 confining there within the central opening 74 of the gasket 74 and the diaphragm 72.

These switch parts are so assembled together in tight sealing engagement with the top of the flange 58 of the bottom section 38 by the top box section 40 and the screws 42 extending through corner holes 74" and 72' of the respective parts 70, 74, and 72 and into threaded holes 46 of the flange 58.

A depending tack-like member 84 having a flat head 84' and a lower ball end 84" is fastened by its head to the center of the lower face of the diaphragm by a rubber patch 85 surrounding the head and adhered to the diaphragm face.

A sectional pipe assembly 86 depends from the bottom section 38 of the casing 36. This pipe is formed of an upper section 88 with its top end screw threaded into the bottom wall 52 of the bottom section 38 of the device and holding the pipe section 88 rigidly in position thereon. A lower pipe section 90 is attached to the lower end of upper section 88 by means of a sleeve 92 spanning the joint between the pipe sections. A knurled lock washer 94 is threaded on the upper end of lower pipe section 90 serving as a seat for the sleeve 92. A compression spring 95 is threaded about the threaded end of pipe section 88 passing through bottom section wall 52 and upward thereof to provide a centering stud for the spring 95 and engage the depending member holding patch 85 to force the diaphragm upwardly and to maintain the contacts normally in engagement with one another.

An elongated ball chain line 96 extends loosely through the pipe assembly 86. A crosspiece or washer 98 is fastened to the bottom end of the chain 96 where it extends below the pipe, the washer spanning the opening in the bottom pipe section 90 and extending laterally on both sides thereof, the washer being supported on the chain 96 by a ball-shaped knob 99. The upper end of the ball chain 96 is fastened to ball end 84 of depending diaphragm member 84 by a slit closed end of a connecting member 100 as best seen in FIGS. 3 and 4.

A metal float is slidably mounted on the lower pipe section 90. The float comprises a cylindrical hollow body ,112 with a side wall 114, top wall 116 and a bottom wall 118. The top and bottom walls have aligned openings 120 and 122, respectively with outstanding annular flanges 124 and 126, respectively. A tube 128 extends centrally through the body with its ends fastened to the inner surfaces of upwardly and downwardly turned flanges 124 and 126. The pipe section 90 extends loosely through the tube 128 to allow play for the float in the tank liquid.

In practicing the invention, the length of the switch device 34 will be sufficiently long to extend from above the top of the tank 10 to a predetermined point spaced from the bottom of the tank and above any sludge 130 that may get lodged in the bottom of the tank. The pipe assembly 86 with float 110 thereon will have been extended through an opening 132 in the top of the tank 10 and through an internally threaded neck 134 formed therearound. The externally-screw threaded bottom section 38 of the device is threaded into the neck 134 formed therearound. The externally-screw threaded bottom section 38 of the device is threaded into the neck 134 and sealed on the top thereof by a sealing washer 135. The length of the switch device 34 having first been adjusted by means of the sleeve 92, leaving the flange 58 thereof seated on the top edge of the neck 134 as best seen in FIG. 3. When oil 136 in the tank reaches a predetermined low level, as illustrated in figure, the float 110 will have slid downwardly the end of its bottom flange 126 striking the washer 98 thereby forcing the washer downwardly a slight distance away from the lower end face of the lower pipe section 90 as shown in FIG. 4, the washer pulling the chain 96 and with it the diaphragm 72, thereby automatically breaking the contact between the contact strips 78 and 76.

The circuit including these contact strips and the main control switch 25 thereby being interrupted so that the oil burner 12 cannot be fired until the oil tank 10 is refilled to raise the switch float 110. Before the refilling of the tank the sludge in the bottom thereof may be removed by the usual procedure.

While there has been illustrated and described the preferred embodiments of my invention, it shall be understood that I do not limit myself to the precise construction herein disclosed and that various changes and modifications may be made within the scope of the invention as defined in the appended claim.

What is claimed is:

1. An apparatus of the kind described having an oil tank, with a top opening therein, an oil burner operatively connected to the oil tank, and an electric control switch operatively connected to the oil burner, improved electrical switch mechanism operatively connected to the oil tank, said mechanism including a two-part section having a cylindrical hollow body fitted over the opening in the tank, said one section being open at the top, the other section constituting a cover for the open top of the one section, an electrical contact and diaphragm assembly tightly sealed between the two sections and including a support plate and a flexible diaphragm overlying one another and respectively having contacts normally held in engagement with each other, means for moving said diaphragm and its contact from support plate contact when the level of the oil in the tank reaches a predetermined limit, a stationary electrical contact including an insulating plate, a wafer-thin contact strip secured at one end to the top surface of said plate, and extending around the side edge of the plate end and secured at its other end to the under-surface of said insulating plate, a second Wafer-thin contact strip secured at one end to the top surface of said plate insulatingly spaced oppositely to the first named contact strip, said second contact strip extending around the side edge of the plate, an insulating flexible diaphragm closely spaced underneath the insulating plate, the other end of said second contact strip fastened to the top surface of said diaphragm, said diaphragm being otherwise unattached and covering both contact strips thereby sealing said contact strips from the interior of the tank to prevent sparks reaching the same, the means for moving the movable contact when the level of the oil reaches a predetermined limit including a pipe depending from said one section of the device, the top end of the pipe extending through a hole in the bottom in said one section, to the interior thereof, a line connected to the diaphragm and extending through the pipe with its bottom end protruding outwardly of the bottom end of the pipe, a crosspiece fixed on the bottom end of the line outwardly of the bottom end of the pipe and spanning the bottom end thereof and projecting laterally thereof, a compression spring reacting between the bottom of the first section and the diaphragm to normally keep the contacts opened, and a float slidably mounted on the exterior of the pipe, the crosspiece being in the path of sliding movement of the float whereby when the oil in the tank reaches a predetermined level, the float will strike the crosspiece driving the line downwardly and carrying the diaphragm and second contact strip therealong, thereby separating the contact strips and breaking the circuit through the first-named switch device connected to the oil burner control whereby the oil burner is rendered inoperative.

References Cited UNITED STATES PATENTS 3,211,853 10/1965 Le Corvoisier 200-84 2,894,092 7/ 1959 MacGriff 200-84 1,869,030 7/1932 Teesdale 200-84 BERNARD A. GILHEANY, Primary Examiner.

H. BROOME, Assistant Examiner. 

